Circuit breaker resetting mechanism



Oct. 31, 1967 G. E. GAUTHIER CIRCUIT BREAKER RESETTING MECHANISM Filed Jan. 25, 1965 RESET I 'INVENTOR GEORGE 5 GQUTH/ER WWW- A TTORA/EY I United States Patent 3,356,525 CIRCUIT BREAKER RESETTING MECHANISM George E. Gauthier, Plainville, Comm, assignor to General Electric Company, a corporation of New York Filed Jan. 25, 1965, Ser. No. 427,717 7 Claims. (Cl. filth-116) ABSTRACT OF THE DISQLGSURE A latch trip type circuit breaker has a releasable member normally held by a latch member which is biased toward releasing position by a spring means; the latch member is restrained from movement in releasing direction by another latch means, which is adapted to be moved by current responsive means to initiate opening of the breaker upon the occurrence of predetermined conditions; the first latch is reset into latched engagement with the second latch by means carried by the movable contact arm of the circuit breaker as it moves from closed to open circircuit position during the tripping operation.

The present invention relates to circuit breakers and more particularly circuit breakers which usually have a trip mechanism enclosed within a casing separate from the main insulating casing of the circuit breaker and including a means and arrangement for automatically resetting such trip mechanism upon the actuation of the operating mechanism of the circuit breaker to open its main current conducting contacts when predetermined overload conditions occur.

Circuit breakers of the type referred to usually have several pairs of main current conducting contacts Within a pole chamber with one contact of each such pair being supported in a stationary position while the other contact of each such pair is rendered movable by being supported on a movable means such as a pivoted contact arm. Such contact arms are generally spring loaded for rapid movement from a closed contact position to an open contact position for interrupting the flow of overload currents of predetermined amplitude. The spring-loaded operating mechanism associated with such movable contact arm generally includes a releasable member Which is adapted to be restrained in a latched position holding the contact arm and the relatively movable and stationary pairs of contacts in closed circuit condition. Upon release of the releasable member from its latched position, the springbiased operating mechanism associated with the movable contact arm is actuated to rapidly move the pairs of contacts to open circuit condition, interrupting the flow of overload currents therethrough. Also usually associated with the operating mechanism of the circuit breaker is an externally extending, reciprocally operable handle means Which, upon such actuation to open the pairs of contacts of the circuit breaker, moves pivotally from one reciprocal position to another. In most prior art, conventional circuit breakers of the type referred to, the externally extending, reciprocally operated handle may be positioned in an extreme reciprocal position which position is employed to operatively reset the latch mechanism of the circuit breaker so that the latch mechanism is recycled into its set position and condition before the main current carrying contacts of the circuit breaker are returned to their closed circuit condition by manual operation of the extending handle means of the circuit breaker in the opposite reciprocal position. The present invention, however, provides a means and an arrangement by which the opening movement of the main operating mechanism of the circuit breaker is employed to reset the latch mechanism of the circuit breaker automatically. Thus,

in accordance 3,350,525 Patented Oct. 31, 1967 with the concept of the present invention, the same forces which are employed to open the main current carrying contacts of the circuit breaker are utilized to reset the latch mechanism after it has been actuated to release the main operating mechanism of the circuit breaker.

Accordingly, it is a principal object of the present invention to provide a means for automatically reseting the latch mechanism of a circuit breaker.

Another object of the present invention is to provide such automatic resetting of the latch mechanism of a circuit breaker by employing the same forces which operate to open the main current carrying contacts of the circuit breaker under predetermined overload conditions Yet another object of the present invention is to pro vide an arrangement of means carried by the contact arm of such a circuit breaker for engaging and resetting the latch mechanism of the circuit breaker upon opening movement of its contact arm.

A further object of the present invention is to provide an arrangement which operatively employs the movement of a contact cross arm in a multipole circuit breaker to engage and reset the latch mechanism of such circuit breaker upon opening of its contacts.

A still further object of the present invention is to provide for the resetting of collapsible toggle linkage latch to a set straightened position by utilization of the movement of the contact cross arm upon opening of the main current carrying contacts of the circuit breaker.

In one form, the present invention comprises an electric circuit breaker which includes at least one relatively stationary contact and a relatively movable contact carried on a movable contact arm and aligned to be brought into electrically conductive engagement with the stationary conv tact. An operating mechanism is provided for actuating the movable contact arm, usually in biased movement from a closed to an open circuit position of the aforementioned stationary and movable contacts. The operating mechanism also includes a member which is releasable from a latched position to cause automatic opening of the contacts. A releasable latching mechanism is provided within means are arranged to retain the latching mechanism in its first-mentioned position, restraining the releasable member of the main operating mechanism of the circuit breaker. The current-sensitive means is designed and calibrated to be responsive to overload current conditions of predetermined amplitude to cause the latching mechanism to move to its second named position releasing the releasable member of the main operating mechanism of the circuit breaker thereby opening the main a multipole circuit breaker, for example, is provided and arranged to be operatively responsive to the opening movement of the contact arm to which it is afiixed to for engaging and returning the latching mechanism to its first named position.

In a multipole circuit breaker of the type employed in three phase applications, for instance, suitable collapsible toggle linkage, usually spring biased toward a collapsed position, is arranged to be set in its straightened position. Such toggle linkage in its set straightened position may be adapted to position a latching mechanism to latch the member of the main operating mechanism of the circuit breaker. Upon the occurrence of overload conditions, the current-sensitive means moves 30 as to permit the toggle linkage to be collapsed by the bias forces acting upon it and permitting the consequent release of the releasable member of the main operating mechanism of the circuit breaker from its latched position thereby opening the main current carrying contacts of the circuit breaker and interrupting the flow of overload current therethrough. After the movable contact arm has initiated its contact opening movement, suitable means carried by the contact arm such as a contact cross arm is moved into engagement with a portion of the latching mechanism which may be a pivotable extension of one of the aforementioned toggle links. The substantially greater bias force of the main operating mechanism of the circuit breaker overcomes the lesser bias of the latching mechanism to reset the togglelinks in their straightened set position so that the releasable member of the main operating mechanism of the circuit breaker is engageable in latched and restrained position to permit reclosing of the main current carrying contacts of the circuit breaker by actuating of the main operating mechanism through positioning the externally extending handle means in the appropriate extreme reciprocal position.

These and other objects and features of the present invention will be more fully understood from the following detailed description together with the accompanying drawings and its scope will be pointed out in the appended claims.

In the drawings,

FIGURE 1 is a side elevational, partially cross-sectional, cut-away view of a circuit breaker embodying the present invention;

FIGURE 2 is a side elevational, partially cross-sectional view of the co-acting elements of the present invention as embodied in the circuit breaker illustrated in FIG- URE 1;

FIGURE 3 is a side elevational, partially cross-sectional view of the co-acting elements illustrated in FIG- URE 2 illustrating the operation of the tripping mechanism upon the occurrence of overload currents; and

FIGURE 4 is aside elevational, partially cross-sectional view illustrating the automatic resetting operation of the co-acting elements of the present invention as embodied in the circuit breaker of FIGURE 1.

Referring now to FIGURE 1, there is shown a circuit breaker incorporating an embodiment of the present invention. The circuit breaker of FIGURE 1 comprises a main molded insulating casing which houses a plurality of incoming and outgoing terminal means 11 and 12, respectively, only one of each being shown. In a multipole circuit breaker of the type illustrated in FIG- URE 1 which carries a substantial current, several pairs of relatively movable contacts such as those shown at 13 and 14 and 15 and 16 may be connected between each incoming terminal as shown at 11 and its corresponding outgoing terminal as shown at 12. The pair of relatively movable contacts 13 and 14 are arcing contacts while the main current carrying contacts may comprise several pairs such as the pair shown at 15 and 16. The stationary contacts 14 and 16 are rigidly supported on a conductor 17 while the movable contacts 13 and 15 are supported upon a movable contact arm 18 which is supported at its ends on suitable bearing means (not shown) which bearing means are in turn mounted suitably in the base of the insulating casing 10.

In a multipole circuit breaker of the type illustrated in FIGURE 1, a contact cross arm 19 extends across the plurality of poles of the circuit breaker and is rigidly fixed to a number of contact arms similar to that shown at 18. Each movable contact arm is electrically connected through suitable conductors including a flexible stranded conductor 20 to a terminal strap 21 of the trip unit 22. Each terminal strap of a trip unit such as the strap shown at 21 is connectable electrically through the trip unit to a corresponding outgoing terminal strap as shown at 23. For the purpose of operating the contact arm 18 and moving the plurality of relatively movable contacts from a closed circuit position to an open circuit position, a suitable operating mechanism is provided which includes a reciprocally operable handle 24 extending through an aperture in the insulating casing 10 which handle is pivotably supported and operatively engaged with an overcenter spring mechanism shown generally at 25 and including a releasable member 26. The releasable member 26 has a latch portion 26a which is configured to be engageable and releasably held in a latched position by appropriate means such as the primary latch 27. The reciprocally operable handle 24 may be manually positioned in the off position (to the left in FIGURE 1 as shown by the dash line outline enclosed) causing the several pairs of contacts on the contact arm 18 to disengage thereby interrupting the flow of current through those contacts. Alternatively, current-sensitive means within the trip unit 22 will, upon the flow of overload currents of predetermined amplitude, act upon the latching mechanism causing it to release the releasable member 26 from its latched position and actuating the main operating mechanism 25 ofthe circuit breaker to disengage the several pairs of relatively movable contacts such as those shown at 13 and 14 and 15 and 16. The operation of the latching machanism of the present invention and its coaction in engagement with and response to the opening movement of the main operating mechanism of the circuit breaker will be more fully understood from FIGURES 2, 3 and 4 wherein like members bear the same numerical designations as in FIGURE 1.

Referring now to FIGURE 2, there is shown the releasable member 26 of the main operating mechanism of the circuit breaker which has its latch portion 26a in latched engagement with the primary latch 27. The primary latch 27 is pivotable about a support 28 carried on the main insulating casing of the circuit breaker and is spring biased in a clockwise direction. The primary latch 27 has an extending portion 27a which is configured to be engageable with an adjacent portion of the tripping mechanism of the circuit breaker. The extending portion 27a of the primary latch 27 may be engaged with a rotatably supported latch roller 29 of the tripping mechanism. However, it is to be understood that the present invention may be as well embodied and its concepts executed in a circuit breaker which employs a tripping mechanism directly engaged with the main operating mechanism of the circuit breaker and its releasable member as well as effecting such engagement through a primary latch such as 27 shown in the particular embodiment illustrated in FIGURES 1, 2, 3 and 4. As illustrated in FIGURE 2, the latch roller means 29 which is extended to engage the primary latch 27 and position the primary latch 27 in latched engagement with the releasable member 26, is movably positionable by reason of being supported at a movable pivot point joining a link 30 and the toggle link 31. The link 30 is supported from a boss 32 aflixed to the insulating casing of the trip unit 22. The latching mechanism in the embodiment of FIGURE 2 includes a pair of toggle links 31 and 33 which are joined at a common pivot point 34, the toggle link 33 being pivotable about a point 35 so that the pair of toggle links 31 and 33 are collapsible about their common point 34 in response to the bias of a spring 36 acting upon the knee pivot point 34. The toggle links 31 and 33 are disposed and arranged to be positionable in a straightened set position as illustrated in FIGURE 2 so as to cause the releasable member 26 to be restrained in its latched position by the primary latch 27. The toggle links 31 and 33 are retained in their straightened set position by reason of the toggle link 33 being latched to latch 37 of a trip bar 38 which is urged toward the latched illustrated position by a spring bias means 39. A thermally responsive, current-sensitive, means 40 is positioned adjacent the trip bar 38 and upon the occurrence of overload current conditions of a predetermined amplitude becomes heated and displaced to the left in FIGURE 2 so as to bear upon the trip bar 38.

The action of the current-sensitive means will be more clearly seen from the illustration of FIGURE 3 wherein the distorted, thermally responsive, current-sensitive means 40 is shown to be bearing upon the trip bar 38 displacing the trip bar 38 about its pivot point 38a, displacing the latch 37 from its engagement with the end of toggle link 33, allowing toggle link 33 to pivotally rotate in a clockwise direction in response to the bias force exerted upon its knee point 34. Thus the toggle links 31 and 33 are collapsed downwardly, drawing the upper portion of link 30 in a counterclockwise direction about its lower pivotal support in boss 32. Accordingly, the latch roller element 29 is drawn to the left in FIG- URE 3, allowing the bias force acting upon releasable member 26 to displace the primary latch 27 against its oppositely directed bias, thus releasing the releasable member 26 from its position of latched engagement with the primary latch 27. As shown in FIGURE 3 (the releasable member 26 having been released from its latched position as indicated by the dash line outline), the main operating mechanism of the circuit breaker operates under its spring bias to move the contact arm 18 to disengage the pairs of relatively movable and stationary contacts of the circuit breaker to interrupt the flow of overload current therethrough which caused the actuation of the thermally responsive, current-sensitive means 40. It should be noted that in FIGURE 3, the contact arm 18 has begun to move upwardly about its pivot point and at the illustrated point of operation,'the main current carrying contacts of the circuit breaker have just been opened or are about to be opened. As the contact arm 18 continues to move about its pivot point due to the bias force exerted by the main operating mechanism of the circuit breaker, it assumes a position as illustrated in FIGURE 4.

As seen in FIGURE 4, the contact arm 18 has been elevated in pivotal movement about its pivot point, opening the main current contacts of the circuit breaker and interrupting the flow of overload currents. The contact cross arm 19 is seen in FIGURE 4 to have pivoted about the pivot point of contact arm 18 to which it is afiixed to its extreme position against a contact arm stop 41 and one corner of the cross arm 19 has come into engagement with an extending portion 31a of toggle link 31. The pivotal movement of the contact cross arm 19 in a counterclockwise direction tends, by its engagement with the toggle link 31, to move toggle link 31 in a clockwise direction about its pivot point at roller 29. Thus the knee of the toggle links 31 and 33 is drawn upwardly against the spring 36, pivoting the toggle link 33 in a counter clockwise direction and allowing its end to be positioned for engagement by latch 37 of the trip bar 38, Thus the fiow of overload currents having been. interrupted, the thermally sensitive current responsive means 40 will gradually return to its normal position allowing the trip bar 38 to latchingly restrain the toggle link 31. The tripping mechanism of the circuit breaker is thus automatically returned to its reset position. Upon actuation of the externally extending handle 24 from its ofl? position to the reset position, releasable member will be latched by the primary latch 27 as shown by the dash line outline in FIGURE 4, and upon positioning the handle 24 in its on position, the contact arm 18 will be returned to its position of closed engagement of the main current carrying contacts of the circuit breaker.

As will be appreciated by those skilled in the art, the bias force which is exerted by the main operating mechanism of the circuit breaker is substantially greater than the bias force exerted by the tripping mechanism of the circuit breaker and therefore the biased pivotal movement of the contact arms of the circuit breaker is fully suificient and adequate to reset the tripping mechanism against its own counter bias force. Additionally, it will be appreciatedthat in accordance with the concept of the present invention and its automatic operation to reset the tripping mechanism of a circuit breaker, it is not necessary as in prior art circuit breakers to operate the externally extending handle of the circuit breaker to an extreme reset position as indicated by the dash line outline of FIGURE 1 to manually effect resetting of the latching mechanism as the movement of the handle to reset only relatches the releasable member of the main operating mechanism of the circuit breaker. Moreover, the present invention improves the ease of manual and external operation of the cricuit breaker in moving the external handle from its off to its reset position in that the handle need only be positioned against the spring bias forces of the main operating mechanism rather than having to overcome the spring bias forces of the latching mechanism in addition to the main operating mechanism in resetting and placing a circuit breaker in the on condition as was the case with many prior art circuit breakers.

Moreover, the present invention has the advantage of utilizing the spring bias forces and the kinetic energy of the movable contact arms of a multipole circuit breaker so as to dissipate some portion of the force which must otherwise be absorbed by a contact stop arm or equivalently functional means.

It will also be apparent to those skilled in the art that the tripping mechanism of the embodiment illustrated in the drawings herein is but an illustrative configuration used for purposes of explanation and understanding of the invention and its operation. Many different types of tripping mechanisms may be employed, as for instance, the tripping mechanism need not be of a collapsible toggle link type but may be of any other suitable linkage. In alternative embodiments of the present invention, the tripping mechanism need not include a primary latch as disclosed and illustrated herein but may be directly engaged with the main operating mechanism of the circuit breaker or operatively engaged through other appropriate means. The tripping mechanism may also include separate bias means which is arranged to be latched in a set position for impact engagement with suitably disposed linkage which, in turn, will operate to cause the release of the releasable member of the main operating mechanism of the circuit breaker and the consequent opening of the main current conducting contacts of the circuit breaker.

While I have disclosed only certain embodiments of the invention, it will be readily appreciated that many modifications thereof may be made. I therefore intend by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A multipole electric circuit breaker comprising: a main insulating casing; at least two pairs of contacts supported in said casing, each pair comprising a stationary contact and a movable contact carried on a pivotable contact arm; an operating mechanism in said main casing for actuating said pivotable contact arms in biased movement between closed and open circuit positions of said pairs of contacts and including a member releasable to cause automatic opening of said pairs of contacts; a separately enclosed trip unit removably mounted in said main insulating casing; means disposed to releasably engage said trip unit with said releasable member of said operating mechanisms; collapsible toggle linkage carried by said trip unit, said toggle linkage being disposed in its straightened position to cause said last-named means to releasably engage said releasable member of said operating mechanism; bias means operatively disposed to cause the col lapse of said toggle linkage and the release of said releasable member; a common trip bar supported by said trip unit to releasably latch said bias means against collapse of said toggle linkage; at least one current responsive means carried by said trip unit for each of said poles and disposed to cause the release of said toggle linkage bias means upon the occurrence of predetermined overload current conditions. a common contact cross arm rigidly aflixed to said pivotable contact arms for pivotable movement upon the biased actuation of said pivotable t7 Contact arms is open said contacts;- and means ositioned and configured to be engaged by said contact cross arm in its biased pivotal movement, said means being operativ'ely responsive to such engagement to reset said toggle linkage bias means in its latched position.

2. An electric circuit breaker comprising:

(a) a support;

(13') a contact arm supported on said support and movable betvveen open and closed circuit positions;

(c) a releasable member supportedon said support and releasable to cause automatic movement of said Contact arm from said closed to said open circuit position;

(d) latch means supported on said support and having a first position in which it engages said releasable member and restrains said releasable member;

(e) biasing means biasing said latch means for movemerit from said position in which it restrains said releasable member to a releasing position in vvhich it releases said releasable member,

(f) current sensitive means normally engaging said latch means and restraining said latch means in said latching position against the bias of said biasing means, said current sensitive means being responsive to predetermined overload current conditions through said circuit breaker to release said latch means for movement to its releasing position by said biasing means; and g (g) means for returning said latch means to said latching position against the bias of said biasing means, said means comprising means carried by said contact arm and engageable with said latch means upon movement of said contact arm from said closed to said open circuit positions.

3. An electric circuit breaker as set farm in claim 2 wherein said circuit breaker also comprises a main op erating spring acting on said movable contact arm, said operating spring acting upon the release of said releasable member to move said contactarm from said closed to said open circuit position, the bias of said operating spring being substantially greater than the bias of said biasing means acting on said latch means, whereby said main opertaing spring acts through said movable arm to reset said latch means against the bias of said latch biasing 4. An electric circuit breakercomprising:

(a) a relatively stationary contact;

(b') a relatively movable contact carried by a pivotable contact arm; I I

() operating mechanism for actuating said pivotable contact arm between open and closed circuit positions, said operating mechanism including a releasaable member releasable frorna latched position to cause automatic opening of said contacts;

3 I (d) latch means for releasably restraining said releasable member;

(e) biasing means acting on said latch means and biasing said latch means in unlatching direction;

(f) current sensitive means engaging said latch means and retainingsaid latch means in latched position against said biasing means, said current sensitive means being responsive to predetermined overload current conditions to release said latch means from said releasable member;-

(g) means carried by said pivotable Contact and for engaging said latch means upon movement of said contact arm from said closed to said open circuit position for returning said latch means to latching pos'ition against the bias of said latch biasing means;- and (h) said means carried by said contact arm engaging said latch means after the bias force of said operating mechanism spring has been substantially expended, thereafter returning said latch means to its latching position.

5. An electric circuit breaker as set forth in claim 4 wherein said latch means comprises a first pivoted member and a pair or toggle links normally restraining said pivotal member for pivotal movement in unlatching direction, and wherein said latch biasing means, comprises means acting on said toggle linkage and biasing said toggle linkage toward collapsing ct'jndition, and means carried by said movable contact arm for engaging said toggle links and moving said toggle links from said collapsed to said straightened condition against the bias of said biasing means upon movement of said contact-arm from closed to saidopen circuit position.

6. An electric circuit breaker as set forth inclaim 5 wherein said toggle links include a portion extending into the path of the means carried by said contact arm for resetting said toggle links in latched straightened position. v

7. An" electric circuit breaker as set forth in claim 6 wherein said portion of said toggle links extending into the path of said contact arm comprises a portion pivotable about the pivot point of one of said toggle links.

References Cited UNITED STATES PATENTS BERNARD A. GlLHEANY, Primal-y Examiner. H. B. GILsoN, Ania/an: Examiner, 

1. A MULTIPLE ELECTRIC CIRCUIT BREAKER COMPRISING: A MAIN INSULATING CASING; AT LEAST TWO PAIRS OF CONTACTS SUPPORTED IN SAID CASING, EACH PAIR COMPRISING A STATIONARY CONTACT AND A MOVABLE CONTACT CARRIED ON A PIVOTABLE CONTACT ARM; AN OPERATING MECHANISM IN SAID MAIN CASING FOR ACTUATING SAID PIVOTABLE CONTACT ARMS IN BIASED MOVEMENT BETWEEN CLOSED AND OPEN CIRCIT POSITIONS OF SAID PAIRS OF CONTACTS AND INCLUDING A MEMBER RELEASABLE TO CAUSE AUTOMATIC OPENING OF SAID PAIRS OF CONTACTS; A SEPARATELY ENCLOSED TRIP UNIT REMOVABLY MOUNTED IN SAID MAIN INSULATING CASING; MEANS DISPOSED TO RELEASABLY ENGAGE SAID TRIP UNIT WITH SAID RELEASABLE MEMBER OF SAID OPERATING MECHANISMS; COLLAPSIBLE TOGGLE LINKAGE CARRIED BY SAID TRIP UNIT, SAID TOGGLE LINKAGE BEING DISPOSED IN ITS STRAIGHTENED POSITION TO CAUSE SAID LAST-NAMED MEANS TO RELEASABLY ENGAGE SAID RELEASABLE MEMBER OF SAID OPERATING MECHANISM; BIAS MEANS OPERATIVELY DISPOSED TO CAUSE THE COLLAPSE OF SAID TOGGLE LINKAGE AND THE RELEASE OF SAID RELEASABLE MEMBER; A COMMON TRIP BAR SUPPORTED BY SAID TRIP UNIT TO RELEASABLY LATCH SAID BIAS MEANS AGAINST COLLAPSE OF SAID TOGGLE LINKAGE; AT LEAST ONE CURRENT RESPONSIVE MEANS CARRIED BY SAID TRIP UNIT FOR EACH OF SAID POLES AND DISPOSED TO CAUSE THE RELEASE OF SAID TOGGLE LINKAGE BIAS MEANS UPON THE OCCURRENCE OF PREDETERMINED OVERLOAD CURRENT CONDITIONS, A COMMON CONTACT CROSS ARM RIGIDLY AFFIXED TO SAID PIVOTABLE CONTACT ARMS FOR PIVOTABLE MOVEMENT UPON THE BIASED ACTUATION OF SAID PIVOTABLE CONTACT ARMS TO OPEN SAID CONTACTS; AND MEANS POSITIONED AND CONFIGURED TO BE ENGAGED BY SAID CONTACT CROSS ARM IN ITS BIASED PIVOTAL MOVEMENT, SAID MEANS BEING OPERATIVELY RESPONSIVE TO SUCH ENGAGEMENT TO RESET SAID TOGGLE LINKAGE BIAS MEANS IN ITS LATCHED POSITION. 